如果x+y=1,那么0.5x²+xy+0.5y²的值是多少
问题描述：
如果x+y=1,那么0.5x²+xy+0.5y²的值是多少
答
因为x+y=1所以（x+y）^2=x^2+2xy+y^2=1，
0.5x^2+xy+0.5y^2=2(x^2+2xy+y^2)/4=1/2
答
x+y=1
(x+y)²=1
(x+y)²/2=1/2
x²/2+xy+y²/2=1/2
0.5x²+xy+0.5y²=0.5
答
0.5x²+xy+0.5y²
=0.5(x²+2xy+y²)
=0.5(x+y)²
=0.5
答
0.5x²+xy+0.5y²
=0.5(x^2 + 2xy +y^2)
=0.5*(x+y)^2
=0.5*1^2
=0.5